BERKELEY, CA – Scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory can now control how cells connect with one another in vitro and assemble themselves into three-dimensional, multicellular microtissues. The researchers demonstrated their method by constructing a tailor-made artificial cell-signaling system, analogous to natural cell systems that communicate via growth factors.
Their method of attaching the DNA uses artificial sugars. They are working on other ways to attach the DNA.
The researchers enabled cells to react with other cells in a controlled way by coating the cell surfaces with DNA (not where DNA is normally found!). First they induced the cells to express artificial sugars bearing special chemical groups. Lengths of synthetic DNA, introduced into the cell-growth medium, were equipped to recognize these synthetic sugars on the cell surfaces and chemically bind to them.
They were able to combine two cell types where one cell type needed the other cell type.
Bertozzi and Gartner applied these methods to build a signaling network where one kind of cell controls the growth of a second kind of cell. They maintained the survival and replication of hematopoietic progenitor cells (a kind of stem cell for blood cells), which depend on the presence of the growth factor interleukin-3, by combining them in microtissues with CHO cells (Chinese hamster ovary cells) that were engineered to secrete interleukin-3.
When the two cell types were randomly mixed, the stem cells didn’t grow. But structured microtissues built from the two cell types stimulated their own growth, forming a simple artificial signaling network that behaved much like the natural networks that control immune-cell expansion or tumor proliferation.
Tissue engineering to create organs outside of the body is a difficult problem. We need ways to grow or build replacement organs. One way is to genetically engineer pigs to grow human-compatible organs. Another way might be to create a really complex chemical environment that'll act like an artificial womb that only grows part of the body. But some researchers such as the Lawrence Berkeley folks are just trying to build up organs with methods for laying down cells in 3 dimensions. My guess is all these approaches have a future with each suited better to particular organs.
|Share |||Randall Parker, 2009 March 09 11:04 PM Biotech Tissue Engineering|